FIGS. 1-2 show perspective and side views, respectfully, of a wheel suspension 100 of a multilink rear axle for a vehicle. Such a configuration is known as a trailing arm axle. Although only a single wheel suspension 100 is illustrated in FIGS. 1-2, normally a second wheel suspension would be arranged on the opposite side of the vehicle. The wheel suspensions on opposite sides of the vehicle (e.g., in a width direction of the vehicle) can be mirror images of each other.
Each wheel suspension 100 has two lower control arms 103 and 104, an upper control arm 105, and a trailing arm 106. The control arms 103, 104, and 105 are coupled to a wheel carrier or knuckle 107 and are capable of pivoting (e.g., rotating in a plane transverse to a longitudinal direction of the vehicle) about pivot points 112, 113 and 114 via respective bushings 109, 110, and 111. A wheel (not shown) can be attached to the wheel carrier 107 via bolts 108.
The three control arms 103, 104, and 105 extend parallel to each other and approximately parallel to the width direction of the vehicle, i.e., the vehicle horizontal (FH), and to wheel axis X-X. At respective ends opposite to the pivot points 112, 113, and 114, the control arms 103, 104, and 105 can be coupled to the vehicle body via respective bushings 115, 116, and 117 that allow the control arms to pivot (e.g., rotate in a plane transverse to the longitudinal direction of the vehicle).
A longitudinal suspension arm, or trailing arm, 106 is an elongated plate extending away from the wheel carrier 107, for example, along the longitudinal direction toward a front of the vehicle. The trailing arm 106 thus has low torsional resistance and allows for flexing or bending about the vertical axis. The trailing arm 106 is coupled at one end to the vehicle body via a bushing 118 and at an opposite end to the wheel carrier 107. The bushing 118 allows trailing arm 106 to pivot (e.g., rotate about the illustrated Y-axis). The trailing arm 106 acts to absorb forces in the vehicle longitudinal direction as well as control the trajectory of the rear wheel during spring element compression and extension of spring element 119.
A damper (not shown) and spring element 119, e.g., a coil spring, are provided to support the vehicle body or frame on the wheel suspension 100. A spring plate 120, which is formed as part of the rear lower control arm 104, holds the spring element 119. Because the cross-sectional profile of the rear lower control arm 104 is adapted to provide the spring plate 120, the lower control arm 104 has a relatively low stiffness. As a result, the vehicle driving performance, for example, its steering behavior and steering feel transmitted to the driver, may be adversely affected.
The spring plate 120 and spring element 119 are offset toward the rear of the vehicle (i.e. to the right in FIG. 2) with respect to a vertical line A-A running through the center Z of the wheel and with respect to the horizontal wheel axis X-X running through the center Z of the wheel. Consequently, vertical forces generated by spring element 119 (spring force=FS) that act on the wheel suspension 100 via the spring plate 120 and vertical contact forces acting on the wheel body (wheel force=FW) that are transmitted to wheel carrier 107 along line A-A are offset from each other, e.g., by offset 151, as shown in FIG. 2. This causes a vertical force or preload (FTB) on the body-side bushing 118 of the trailing arm 106, which may negatively affect the service life of the body-side bushing 118.
For stabilization, an anti-roll bar 121 is used to provide a rigid connection between the wheel suspensions on opposite sides of the vehicle. The anti-roll bar 121 extends parallel to the vehicle horizontal FH and is attached at its ends to the lower rear control arms 104 via a respective pendulum arm. The anti-roll bar 21 can be attached via symmetrically arranged brackets 136 to the vehicle body or a frame connected to the vehicle body. For example, brackets 136 (of which only the left bracket is shown in FIG. 1) can take the form of a clip adapted to the cross-section of the anti-roll bar 121.
In the multilink axle illustrated in FIGS. 1-2, the use of the anti-roll bar, spring elements, fixing elements, and support points, such as the spring plate on the lower control arm, results in a heavier rear axle in addition to the other disadvantages noted above.
With this in mind, the object of the present disclosure is to provide a rear wheel axle which offers the dynamic driving properties of a structurally complex multilink rear wheel suspension, but which has increased durability and is less susceptible to material wear as compared to the above described trailing arm axle. Furthermore, the object of the present disclosure is to provide a lighter and more compact rear axle which has improved, or at least equivalent, dynamic driving properties.